Method of enhancing the safety of liquid fuel



Aug. 23, 1938. P. SCHLUMB OHM 2,127,536

METHOD OF ENHANCING THE SAFETY OF- LIQUID FUEL Filed 0ct. 12, 1955 II? wi l Ilql ll'll'l Patented Aug. 23, 1938 METHOD or snrrancmc THE SAFETY or v moon) FUEL Peter Schlumbohm, New York, N. Y.', assignor of fourteen percent to George Von Seebeck, New

York, N. Y.

Application October 12, 1935, "Serial No. 44,801

In Great Britain January 24, 1935 10 Claims.

The present invention relates to the storage of fuel both for keeping purposes as well as for storage during use, as for example in the fuel tank of an engine.

More particularly, the invention relates to the storage of fuel of a volatile nature, e. g., petrol, benzene, which readily forms explosive mixtures with air.

The object of the invention is to provide a method of enhancing the safety of the fuel during storage whereby danger of the substance inflamlng or exploding during the storage is reduced to a minimum.

With this object in view the invention consists in adding carbondioxide ,at low temperatures to the fuel and in storing the mixture of fuel and carbon dioxide at low temperatures. Carbon dioxide is especiallysuitable if the fuel is petrol or benzene as used for automobiles and aeroplanes; due to the reciprocal solubility of carbondioxide in petrol and of petrol in liquid carbon dioxide, this system petrol/carbondioxide has special ,physico-chemical properties, especially at low temperatures, which were found to be valuable for the purpose set forth. The system petrol/carbondioxide is e. g. superior to the system petrol/nitrogen, if low temperatures are applied. Generally speaking, the invention consists in cooling the liquid fuel by means of refrigeration to low temperatures and in saturating the fuel at this low temperature with a gas which does not form explosive mixtures with the vapours of the fuel.

An important feature of the invention is to establish the low temperature system petrol/carbondioxide by adding directly solid carbondioxide into the petrol, thus using the carbondioxide ice both as a refrigerant. and as a source of the carbondioxide which is to be added to the petrol. Under these circumstances, temperatures of C. can be reached and maintained for the mixture; the temperature may, however, be above this, if the maximum effect is not aimed at.

'It is understood that the mixture might also be obtained without using solid carbondioxide; the fuel might be cooled down to low temperatures by means of a refrigerating machine and carbondioxide gas might be added until a certain saturation" has been effected. Another .way 'would be to cool down the fuel by means of a refrigerating machine e. g. to 30 C. and to add then solid carbondioxide ice into the cold fuel for the purpose of saturating the fuel with carbondioxide gas.

against fire. It was found experimentally that e. g. a burning torch can be extinguished by immersing the torch-even slowly-into the mix-v ture, and that a flame, e. g. a burning match, can be extinguished by pouring themixture on the flame. The effect is to be explained by two facts; the low'vapour pressure at the low temperature. prevents the quick formation of great masses of vapours of the fuel, and on the other hand the cold fuel is rich in carbondioxide which is evolved from the fuel when the fuel gets warmed by the flame. The effect of carbondioxide gas on flames is known. I

The mixture has to be stored in a tank which is heat insulated or otherwisekept at low temperature.

In order to make use of the invention for the safety of automobiles or aeroplanes, such a storage 'tank with unburnable petrol" must be equipped with additional means in order-to supply .the motor with burnable petrol of normal quality.- For this purpose the petrol which is drawn from the storage tank must be heated and thus degassed on its way from the storage tank to the carburetor. The coldness of the mixture is used for practical refrigeration and cooling purposes, e. g.'for conditioning the air and for keeping foodstuffs. This cooling is preferably effected in countercurrentheat exchangers. It is particularly advantageous to use the mixture for refrigeration and cooling while on its way to the motor. In this way the fuel mixture gets warmed up, e. g. to the temperature of the surrounding air, prior to reaching the engine, the carbondioxide being expelledthereby at the same time. The separation of the expelled carbondioxide from the petrol can beobtained by known technical devices, as illustrated in Fig. 2 of the accompanying drawing, partly in cross-section, partly in view.

Fig. 1 illustrates, partly in cross-section, partly in view, and fully diagrammatically, the general installation of heat exchangers 'as used for warming up the fuel mixture on its way from the, storage tank to' the carburettor of an aeroplane, e. g.

Fig. 2is an arrangement to show an apparatus for separating the gaseous carbon dioxide,'which has been evolved from the fuel mixture under the influence of heat conveyed by the heat exchangers,'from'the liquid fuel which enters the carburettor. 3

The expansion energy of the carbondioxide liberated from the fuel may be used to raise the liquid fuel to a higher level than the storage vesthe ' that the owner of the filling station or even his customer, might use the coldness of the petrol for practical refrigeration purposes.

The invention opens a new market for the manufacturers of carbondioxide ice, and it will lower considerably the costs of this substance for refrigerating purposes, as part of the costs of the applied carbondioxide ice have to be calculated as to be paid for the safety factor.

In Fig. l, the storage tank I of an aeroplane is partly shown. The tank is equipped with heat insulation 2, and the mixture of e; g. gasoline and a certain percentage of carbondioxide passes from the storage tank I to the carburettor I3 of the motor i l, by means of a tube 3. This tube 3 is used for effecting heat exchange between the fuel and brine, air, or other cooling means as to be applied for refrigeration purposes. In Fig. 1, three countercurrent heat exchangers are illustrated in order to dispose of practical refrigeration at three different temperature levels. The

i first heat exchanger in connection with tube 3 is illustrated diagrammatically by the circuit system 4, 5, 6, in which 6 indicates a pump 6, pumping a brine through the circuit system in the sense of the arrows shown. The second countercurrent heat exchanger is illustrated by the circuit system l, 8, 9, in which 8 indicates a pump for pumping the brine through the circuit system in the sense of the arrows shown. The third countercurrent heat exchanger is illustrated by the tubing system Ill, l2, through which air passes in the sense of the arrows shown under the influence of a propeller II. The tube 3 has preferably the form of a spiral 3a within the tube I 0, to offer greater surface for the heat exchange.

Instead of leading from the tube It) directly to the carburettor IS, the installation as illustrated in Fig. 1, could be substituted atpart A-A by the arrangement as shown in Fig. 2. In Fig. 2 an arrangement is shown to separate the gaseous carbondioxide which has been evolved from the fuel mixture under the influence of the heat conveyed to the mixture by the heat exchangers, from the liquid fuel which enters the carburettor II. This separation is effected, following the invention, by creating a liquid trap l5, IE, to the effect that the gaseous carbondioxide passes through tube l8 and a check valve it into the suction tube of the motor where the liquid fuel enters into the carburettor I! after having passed the U-shaped system l5, Hi. This arrangement has the advantage that the automatic inlet control, swimmer needle or the like, of the standard carburettor can be applied, as no difficulties can arise from gas bubbles.

The degree of safety will depend on the percentage of carbondioxide added to the liquid gasoline and rather wide variations are possible. A proportion of 25% in weight of carbondioxide added to in weight of gasoline, would be suflicient protection in many cases.

Having now particularly-described the nature of my invention, and disclosed the manner in which it is to be performed,

What I claim is:

l. The method bf enhancing the safety of liquid fuel during the storage and use thereof, by cooling the liquid fuel to low temperatures, and by dissolving in the fuel at this low temperature a gas which does not form explosive mixtures with the vapours of the fuel.

2. The method of enhancing the safety of liquid fuel during the storage and use thereof, by cooling the liquid fuel to low temperatures, and by dissolving in the fuel at this low temperature a gas which does not form explosive mixtures with the vapours of the fuel, the gas being a gas which in its liquid state would show mutual solubility with the liquid fuel.

3. The method of enhancing the safety of liquid fuel during the storage and use thereof, by cooling the liquid fuel to low temperatures, and by dissolving in the fuel at this low temperature a gas which does not form explosive mixtures with the vapours of the fuel, said dissolved gas being carbondioxide.

4. The method of enhancing the safety of liquid fuel during the storage and usethereof, by cooling the liquid fuel to low temperatures, and by dissolving in the fuel at this low temperature a gas whichdoes not form explosive mixtures with the vapours of the fuel, said dissolved gas being carbondioxide, and said cooling being effected by means of solidified carbondioxide.

5. The method of enhancing the safety of liquid fuel during the storage and use thereof,

by cooling the liquid fuel to low temperatures,

and by dissolving in the fuel at this low temperature a gas which does not form explosive mixtures with the vapours of the fuel, said dissolved gas being carbondioxide, the cooling of the liq-- uid and the dissolving of the gas being effected at the same time by adding solid carbondioxide directly into liquid gasoline.

6. In the method of enhancing the safety of liquid fuel during the storage and use thereof, by cooling the liquid fuel to low temperatures, and by dissolving in the fuel at this low tempera-. ture a gas which does not form explosive mixtures with the vapours of the fuel, the inventive step of warming the mixture of the liquid fuel and the gas on its way to the carburettor of a motorby means of heat exchangers.

'7. In the method of enhancing the safety of liquid fuel during the storage and use thereof,

by cooling the liquid fuel to low temperatures. and by dissolving in the fuel at this low temperature a gas which does not form explosive mixtures' with the vapours of the fuel, the inventive step of warming the mixture of the liquid fuel and the gas on its way to the carburettor of a motor by means of heat exchangers, said heat exchangers being adapted to supply cold to air conditioning equipment.

8. In the method of enhanching the safety of liquid fuel during the storage and use thereof, by cooling the liquid fuel to low temperatures, and by dissolving in the fuel at this low temperature a gas which does not form explosive mixtures with the vapours of the fuel, theinventive step of warming themixture of the liquid fuel and the gas on its way to the carburettor of a motor by means of heat exchangers, said heat exchangers being adapted to supply cold for cold storage purposes. a

9. In the method of enhancing the safety of liquid fuel during the storage and use thereof, by cooling the liquid fuel to low temperatures.

and by dissolving in the fuel at this low tempera- 75 ture a gas which does not form explosive: mixtures with the vapours oi the iuel, the inventive step of warming the mixture oi the liquid fuel and the gas on its way to the carburettor of a motor bymeans or heat exchangers, and providing a liquid trap adapted to separate evolved gas from the liquid and means for conducting the separated gas to the suction tube of the motor.

10. In the method of enhancing the safety oi liquid fuel during the storage and use thereoi,

by cooling the liquid fuel to low temperatures, and by dissolving in the fuel at this low temperature a gas which does not form explosive mixtures with the vapours of thei'uel, the inventive step of warming the mixture of the liquid fuel and the gas on its way to the carburettor of a motor by means of heat exchangers, and providing a liquid trap adapted to separate evolved gas from the liquid and conducting said separated liquld to the carburettor of the motor.

PETER SCHLUMBOHM 

